Physical disturbances can play a major role in the creation and maintenance of landscape heterogeneity, ecosystem processes, and population and community dynamics. Pickett and White (1985:7) defined disturbance as “any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment.” Many natural processes (e.g., fires, floods, volcanic eruptions) and human impacts (e.g., timber harvest and mining) are considered disturbances under this definition. The effects of a disturbance depend not only on the type and magnitude of the disturbance, but also on the timing and frequency of its recurrence. Catastrophic disturbances can eliminate species, reduce biotic diversity, and alter community structure (Petraitis et al. 1989; Pickett et al. 1989). In contrast, less severe disturbances may result in increased biotic diversity by reducing abundances of competitively dominant species (Connell 1978; Petraitis et al. 1989), and/or increasing structural heterogeneity. Disturbances that occur at predictable intervals or as a result of seasonal phenomena can be integral to the functioning of ecosystems that have developed under such regimes. Unexpected events and anthropogenic activities including management practices (e.g., prescribed burns and controlled releases from reservoirs) may occur at times contrary to natural disturbance cycles.

Wildfires are one example of a disturbance that affects systems at the landscape scale and can be important for the maintenance of biotic composition and diversity within those systems. Wildfires create a mosaic of habitat types that benefit many species.